Vehicle locator system

ABSTRACT

A compression type matrix switch comprising rows of parallel horizontal conductors in one plane and columns of parallel vertical conductors in a second plane parallel to the first plane and spaced therefrom by a resilient mat having apertures therethrough at the crossover points of the horizontal and vertical conductors is located behind a beat map overlay in a police patrol car. One end of each conductor is connected to a different sensor that monitors the electrical continuity between conductors at associated horizontal and vertical crossover points. The location of the car is selected for transmission to a monitor facility by firmly pressing the map at the crossover point nearest the actual location of the car. This electrically connects a pair of horizontal and vertical conductors through an aperture in the mat so that the output signals of only the two associated sensors indicate continuity at the crossover point. The outputs of all the sensors comprise a binary code signal uniquely defining the location of the car. This code signal is coupled, together with a binary code signal identifying the car, through a shift register to a transceiver for transmission to the monitor facility. Binary signals received at the monitor facility are processed in a logic circuitry for presenting on a map a visual indication of the location of the patrol car.

Penwarden VEHICLE LOCATOR SYSTEM [75] Inventor: Kent A. Penwarden, LosAltos,

Calif.

[73] Assignee: E-Systems Incorporated, Dallas,

Tex.

[22] Filed: Sept. 11, 1972 [21] Appl. No.: 287,631

Related U.S. Application Data [63] Continuation of Ser. No. 44,219, June8, 1970,

abandoned.

[52] U.S. Cl. 340/24, 178/18 [51] Int. Cl 608g 1/12 [58] Field of Search340/22, 23, 24; 178/18, 19; 200/159, 46

[56] References Cited 1 UNITED STATES PATENTS 3,281,779 10/1966 Yeiser340/23 3,308,253 3/1967 Krakinowski 178/18 3,461,454 8/1969 Steckenrider340/24 3,128,458 4/1964 Romero..: 200/46 3,286,028 11/1966 Gray et a1.178/18 Primary Examiner-William C. Cooper Assistant ExaminerThomas L.Kundert Attorney-James D. Willborn [57] ABSTRACT A compression typematrix switch comprising rows of parallel horizontal conductors in oneplane and columns of parallel vertical conductors in a second planeparallel to the first plane and spaced therefrom by a resilient mathaving apertures therethrough at the crossover points of the horizontaland vertical conductors is located behind a beat map overlay in a policepatrol car. Oneend of each conductor is connected to a different sensorthat monitors the electrical continuity between conductors at associatedhorizontal and vertical crossover points. The location of the car isselected for transmission to a monitor facility by firmly pressing themap at the crossover point nearest the actual location of the cargThiselectrically connects a pair of horizontal and vertical conductorsthrough an aperture in the mat so that the output signals of only thetwo associated sensors indicate continuity at the crossover point. Theoutputs of all the sensors comprise a binary code signal uniquelydefining the location of the car. This code signal is coupled, togetherwith a binary code signal identifying the car, through a shift registerto a transceiver for transmission to the monitor facility. Binarysignals received at the monitor facility are processed in a logiccircuitry for presenting on a map a visual indication of the location ofthe patrol car.

4 Claims, 3 Drawing Figures DECODE CIRCUIT BUFFER REGISTER SHlFTREGlSTER TRANSCEIVER PATENIEBJAH mm sum 2 or 2 INVENTOR, KENT A.PENWARDEN AGENT 1 VEHICLE LOCATOR SYSTEM This is a continuation ofapplication Ser. No. 44,2 I 9, filed June 8, 1970 andnow abandoned.

BACKGROUND OF INVENTION The Police Department of a medium size cityhaving a population of 300,000may have as many as 30 police cars on dutyat one time. .In order to maintain a current and accurate record of thestatus of the location of all patrol cars, the officerin eachpatrol carperiodically calls the dispatcher to report his location. Each of thesemessages is verbally acknowledged by the dispatcher who then manuallyenters the information on a status board. Operation in' this mode crowdsthe available communication channels with routine messages and preventsthe dispatcheraaddressing the more important tasks requiring hisattention. One of the several prior art techniquesproposeduforautomatically accomplishing this function is to place ineach car a transmitter periodically transmitting at a uniquecharacteristic frequency, to place several receiving antennas atdifferent locations around the city, and to triangulate on receivedsignals to determine a vehicles location. Such systems are complex andexpensive.

An object of this invention is the provision of a simple and inexpensivevehicle locator system.

SUMMARY OF INVENTION A unique binary code signal identifying thelocation ofa vehicle is selected for transmission to amonitor facilityby depressing aimap overlay on a compression type matrix switch at acrossover point of two conductors on the latter. The code signal isprocessed at the monitor facility for displaying the vehicle location.

DESCRIPTION OF DRAWINGS FIG. 1 isa schematictand block diagram of asystem embodying this invention;

FIG. 2 is a plan view of a compression typematrix switch; and

FIG. 3 is a section view of thematrix switch in FIG. 2 taken along thelines-3--3.

DESCRIPTION or PREFERRED EMBODIMENT 'shift register and transceiver 11electrically connected in series between the outputs of the sensors andantenna 12. It will be understood that the terms vertical and horizontalare used by way of example and not by way of limitationThe'outputs ofsensors Se-Sh are also applied to OR gate 14 which controls theoperation of clock-control circuit 15 and thus the operation ofauxiliary data circuit 16. Circuitry located in the monitor facility forpresenting a visual display of the location of the patrol car comprisesantenna 17, transceiver l8, logic circuit 19 and display device 20.

Switch 1 is a compression type matrix switchwh'ich is shown in schematicform in FIG. 1. Referring now to FIGS. 2 and 3, the switch comprises apair of printed circuit boards 23 and 24 that are spaced apart by adielectric pad 25 and housed in a frame 26. The circuit boards 23 and 24are preferably flat and located in planes that are parallel to eachother. A map overlay 27 of the beat to be patrolled by the police car,for example, is placed on top of circuit board 24 within the frame.

Printed circuit board 23 is preferably a rigid structure having theparallel strip conductors 2a-2d formed on one side of a rigid dielectricsheet 29. Input terminal pins 32a-32d are electrically connected to oneend of strips 2a-2d, respectively, for making electrical connection toexternal circuitry. The pins 32a-32d are electrically insulated from theframe by the dielectric spacers 33a-33d, respectively.

Printed circuit board 24 is preferably a flexible member having theparallel strip conductors 32-312 formed on the side of aflexibledielectric sheet 34 facing the conductors 2. The circuit boards23 and 24 are oriented in the frame 26 to make the strips 2 and 3orthogonal as illustrated in the FIGURES. Thus, conductors 2 and 3 crossover each other at the points 35 as shown in FIG. 2. A crossover pointis defined as the area over which a pair, of conductors 2 and 3 overlap.The conductors 2 and 3 are normally electrically insulated from eachother at the crossover points by the pad 25 as described more fullyhereinafter. Output terminalpins 36e-36h, which are insulated from theframe by dielectric spacers 37e-37h, are connected to one end of strips3e-3h, respectively, for making electrical connection to externalcircuitry.

Pad 25 is preferably made of a memoryless resilient dielectric materialsuch as sponge rubber. The pad normally electrically insulates theconductors 2 and 3 from each other, the height of the pad being equal tothe spacing between these conductors when the resilient pad is relaxed.An aperture 38 is formed in the pad at each crossover point. The crosssections of the apertures are preferably circular, although they mayalso be of other shapes. The switch is closed at a selected crossoverpoint 39, for example, by an officer in the patrol car pressing with hisfinger on the map at this point to compress the pad until conductors2dand 3f are in physical contact to make electrical connectiontherebetween. This causes pins 32d and 36f, and associated circuitryto'be electrically connected through the aperture at this crossoverpoint.

Alternatively, pad 25 may be made of a non-resilient material such asmylar. In this switch the diameter of the cylindrical apertures 38 aresufficiently large that a flexible conductor 3 deforms into an apertureto contact an associated conductor 2 when an external force is appliedat the associated crossover point.

The horizontal strips 2a-2d are connected through sensors 4a-4a',respectively, andline 41 to a ground reference potential, see FIG. 1.The vertical conductors 7e-7h are connected through sensors 5e-5h andline 42 to the source voltage +V. The outputs of all of the sensors arecoupled on associated lines 430-4311 to the decoder circuit.

The sensors may, by way of example, each comprise the parallelcombination of a resistor and threshold detector connected in serieswith an associated strip conductor of switch 1. The detector monitorsthe voltage developed across the resistor for-producing a binary outputsignal representing the continuity states at associated crossoverpoints. By way of example, when the strips at associated crossoverpoints are spaced apart, no current flows through the resistor and thedetector output is low (a binary indicating that the switch is open.When the strips are electrically connected at an associated crossoverpoint, current flows through and a voltage is developed across theresistor. When this voltage exceeds a prescribed threshold level, thedetector changes operating states such that the output thereof is high(a binary 1) indicating that the switch is closed at one of thecrossover points associated with that sensor.

The outputs of sensors 5 are also connected to OR gate 14 which controlsthe operation of clock-control circuit 15. Circuit 15 produces a controlpulse which is applied on line 44 to the buffer register, on line 45 tothe auxiliary data circuit, and on line 46 to monostable multivibrator47 for illuminating lamp 48 for a predetermined time interval. Circuit15 also produces clock pulses which are applied on line 49 to the shiftregister.

Decoder circuit 8 may comprise logic circuitry for converting the binarysignals (logic levels 1 and 0) from the sensors to a convenient form fortransmission to the monitor facility. By way of example, circuit 8 mayconvert the binary output signals of the sensors to binary numbers thatare applied to the buffer register. This operation of circuit 8decreases the number of bits that are required to represent the binaryinformation from the sensors. Auxiliary information such as: a binaryword representing the identity (ID) of the particular patrol car havingthe map and transmitting its location; a binary synchronization codeword; and, parity bits are produced by auxiliary data circuit 16 andapplied on lines 50 to the buffer register.

Logic circuit 19 may be a computer that is programmed to decode thebinary output signal of the shift register. Alternatively, decoder 8 andcircuit 19 may comprise logic circuits designed in accordance with theteachings of texts such as Logic Design of Digital Computers by M.Phister, Jr., John Wiley & Sons, Inc.

Display 20 in the monitor facility preferably comprises a map similar tothe map overlay 27 on the matrix switch. Lamps 53 are secured to thedisplay map at locations corresponding to each of the crossover pointsof switch 1. Alternatively, the display 20 may comprise a cathode raytube on which a phrase designating the ID of a patrol car and itslocation is printed.

In operation, the output of each of the sensors is low (a logic level 0)when-none of the strips are connected at the crossover points. In thisstate, control circuit 15 is deactivated and a binary signal is nottransmitted by transceiver 11 to the monitor facility. Thus, none of thelamps 53 on display 20 is illuminated. Consider that the location of thecar is found to correspond to the crossover point 39 on the overlay map27. This location information is selected for transmission to themonitor facility by a police officer pressing his finger firmly on themap at point 39. This compresses the pad and causes conductors 2d and 3fto be electrically connected through the associated aperture so that anelectric current is padded through line 41, sensor 4d, conductors 2d and3f, sensor 5f and line 42. When the current passed by sensors 4d and 5fexceeds a prescribed threshold value, the output logic levels of onlythese sensors goes high (a logic level 1). The output of each of theother sensors is low (a binary 0). This combination of binary logiclevels on lines 43 is a unique representation of the location of thevehicle.

Since the output of sensor 5f is now high, OR gate 14 changes operatingstates to activate clock-control circuit 15 for a prescribed timeinterval. Circuit 15 produces a control pulse that causes circuit 16 toenter the ID of the patrol car into the buffer register. This controlpulse also causes monostable multivibrator 47 to change operating statesto illuminate lamp 48 for a predetermined time interval. This tells theofficer in the patrol car that the binary message representing theselected location was transmitted to the monitor facility. The bufferregister is responsive to the control pulse for entering the contentsthereof into the shift register and blocking subsequent input signalsfrom the latter.

After a predetermined time delay, circuit 15 produces clock pulses online 49 which cause the contents of the shift register to be seriallyadvanced on line 54 to the transceiver 11 for transmission to themonitor facility. The contents of the shift register is recirculated online 55 in order to transmit the binary signal a prescribed number oftimes.

The binary signal received by transceiver 18 is processed by logiccircuit 19 which produces an output signal on lines 56 that illuminatesthe lamp 53', corresponding to the crossover point 39, on themap-display 20 to indicate the location of the car. Circuit 19 alsoproduces a code signal on line 57 that is automatically transmitted bytransceiver 18; is addressed to the patrol car; and, indicates that thebinary vehicle location signal from the patrol car was received.Transceiver 11 is responsive to this code signal for producing a signalon line 58 that biases monostable multivibrator 59 to change conductionstates to illuminate lamp 60 for a predetermined time interval. Thistells the officer in the patrol car that his transmitted binary vehiclelocation message was received at the monitor facility.

Changes, modifications and improvements may be made to the aboveidentified preferred embodiment of the invention without departing fromthe spirit of the invention. By way of example, the matrix switch 1 maycomprise as many conductors 2 and 3, and of whatever geometric pattern,as is desired for a particular application. Also, the conductivepatterns and circuit boards supporting them may be three dimensional.Further, although this invention is described as a system for providingan indication of the location of a. police patrol car, it has use inother applications and with other types of objects including a humancarrying the system. The scope of this invention is therefore to bedetermined from the appended claims rather than the above detaileddescription.

What is claimed is:

1. Apparatus for identifying the instantaneous location of a mobile unitat a remote station,

said mobile unit comprising a first map overlay disposed in a firstplane and depicting a geographic area in which said mobile unit islocated,

a compressive-type switch under said map overlay actuatable byfinger-type force applied to said overlay at the point representative ofthe location of said mobile unit, said switch comprising a first set ofspaced parallel conductors in a second plane parallel to said firstplane and a second set of spaced parallel conductors in a third planeparallel to and spaced from said second plane, the conductors of thefirst set extending transversely of the conductors of the second set anddefining therewith crossover points at which electrical contact is madebetween conductors of the two sets in response to said finget-typecompressive force, means for electrically energizing said first set ofconductors, each conductor of the second set being energized only by theconductor of the first set in electrical contact therewith, sensor meansresponsive to the electrical continuity of each conductor of said firstand second sets and producing a first binary digit for each conductor incontact with another conductor and a second binary digit for eachconductor not in contact with another conductor,

means responsive to said first and second binary digits for generating abinary word uniquely defining the selected position of contact betweenconductors of said first and second sets,

a radio frequency transmitter, and

means responsive to said binary word for modulating said transmitter totransmit same to said remote station,

said remote station comprising meansfor receiving said binary word, and

display means responsive to said receiving means comprising a pluralityof illuminatable points adapted to be illuminated to forma patterncorresponding to the pattern of said crossover points of said mobileunit switch with one of said illuminatable points at each positioncorresponding to a crossover point, and

a second map overlay substantially the same as said first map overlayoptically superimposed on said illuminatable points and orientedrelative thereto as said first map overlay is oriented relative to thecrossover points of said switch whereby a finger-type compressive forceapplied to one location on said first map overlay causes illumination ofa point at the same location on said second map overlay.

2. Apparatus according to claim 1 in which said illu- 10 minatablepoints comprise light emitting elements.

3. Apparatus according to claim 1 in which said illuminatable pointscomprise portions of the screen of a cathode ray tube.

4. Apparatus according to claim 1 in which said mobile unit includesmeans for generating a second binary word representing the identity ofthe particular transmitting mobile unit,

' indication means responsive to said transmitting

1. Apparatus for identifying the instantaneous location of a mobile unitat a remote station, said mobile unit comprising a first map overlaydisposed in a first plane and depicting a geographic area in which saidmobile unit is located, a compressive-type switch under said map overlayactuatable by finger-type force applied to said overlay at the pointrepresentative of the location of said mobile unit, said switchcomprising a first set of spaced parallel conductors in a second planeparallel to said first plane and a second set of spaced parallelconductors in a third plane parallel to and spaced from said secondplane, the conductors of the first set extending transversely of theconductors oF the second set and defining therewith crossover points atwhich electrical contact is made between conductors of the two sets inresponse to said finger-type compressive force, means for electricallyenergizing said first set of conductors, each conductor of the secondset being energized only by the conductor of the first set in electricalcontact therewith, sensor means responsive to the electrical continuityof each conductor of said first and second sets and producing a firstbinary digit for each conductor in contact with another conductor and asecond binary digit for each conductor not in contact with anotherconductor, means responsive to said first and second binary digits forgenerating a binary word uniquely defining the selected position ofcontact between conductors of said first and second sets, a radiofrequency transmitter, and means responsive to said binary word formodulating said transmitter to transmit same to said remote station,said remote station comprising means for receiving said binary word, anddisplay means responsive to said receiving means comprising a pluralityof illuminatable points adapted to be illuminated to form a patterncorresponding to the pattern of said crossover points of said mobileunit switch with one of said illuminatable points at each positioncorresponding to a crossover point, and a second map overlaysubstantially the same as said first map overlay optically superimposedon said illuminatable points and oriented relative thereto as said firstmap overlay is oriented relative to the crossover points of said switchwhereby a finger-type compressive force applied to one location on saidfirst map overlay causes illumination of a point at the same location onsaid second map overlay.
 2. Apparatus according to claim 1 in which saidilluminatable points comprise light emitting elements.
 3. Apparatusaccording to claim 1 in which said illuminatable points compriseportions of the screen of a cathode ray tube.
 4. Apparatus according toclaim 1 in which said mobile unit includes means for generating a secondbinary word representing the identity of the particular transmittingmobile unit, indication means responsive to said transmitting means forindicating transmission of said binary words, said remote station havinga transmitter responsive to said receiving means for transmitting anacknowledgment signal upon reception of said binary words, the indicatormeans at said mobile unit also being responsive to said acknowledgmentsignal for indicating reception by the remote station of said binarywords.